1. Field of the Invention
The present invention relates to filling valves, intended for the filling of gas tubes or containers with gas from compressors or pressure containers, preferably from air compressors where the connection to the compressor is by means of the inlet of the filling valve.
2. Description of the Prior Art
Hitherto, needle valves have been used for filling gas containers. Gas containers of this type often are used by personnel in fire brigades, which for their firemen equipped with smoke helmets among other things, use respirators connected to the gas containers. The air, or the gas mixture, that is used for breathing purposes must be completely dry as well as completely clean.
The filling of gas containers is daily work taking place at filling stations and the demands for rapidity and safety in the filling operations must be set high. The demands for safety of the service personnel handling the containers or the tubes at the filling ramps must also be considered, so that damages do not occur to individuals and materials due to unreliable valves. It is also important, for example, when a hose breaks during the filling of gas under elevated pressures, that the risks of damage can be eliminated.
Needle valves, which have been used for the filling of air in gas containers, have a tendency to be worn too fast, principally in the threads, resulting in unacceptable leakage.
A needle valve provided with threads requires for good performance during opening and closing that some kind of lubricating takes place; otherwise, the threads will seize. When the valve is forced to function in dry air, not having any lubricating properties, the valve wears out too rapidly and will become unusable too quickly. As a consequence, there will be large costs for the replacement of needle valves, as their lives are too short. For a filling operation, it is necessary to use two needle valves. As safety in the filling operation is an essential demand, and the drawbacks with initial leakage already after approximately 200 filling operations are evident, it is important to find a better technical solution of the problems encountered in filling gas containers.
To use other types of valves, intended for the filling of other mediums than air, for example, filling valves for liquified petroleum gas, are not possible. The Swedish Pat. No. 350,824 that relates to just such a valve, does not show such constructional features and embodiments that are required because it has a ball-shaped valve body, without small seat and cone areas which are necessary for work with high pressures. This filling valve has no similarities in other respects with the filling valve according to the invention, as it furthermore is intended for the filling of liquified petroleum gas and not for the filling of dry gas, such as air, for example.
Also, other technical solutions such as ball valves provided with throttle nozzles have been tested for the filling of air in tubes and containers. In this case, however, it is necessary to use two valves of that type for the filling operation. This contributes to the fact that the work tends to be difficult as it results in a number of hand operations which do not come in a logical succession. This is obviously a further drawback.
The life of such valves is not especially great either, but may be better than for needle valves. The valves function up to approximately 1,000 filling operations.